i was wondering if there was anyway to test servo extensions to see if they are loseing current or not

you can use an OHM meter, you'll be able to find any breaks or bad connections

A simple continuity check won't always do it. It is a good general check but sometimes a voltage drop test will reveal more. Basically a meter puts out a very small current when testing resistance. If there is any sort of current path at all, this small current will pass right through and the circuit will appear good. Higher current that occurs when in actual operation might cause the resistance to reveal itself though. That's why a voltage drop test on a loaded circuit is generally more accurate. I'd start with a basic resistance check then do a voltage drop if you still suspect a problem.

Regardless of which method is uses, be sure to wiggle and flex the wires to reveal any high resistance or open circuits.

Also, extensions aren't that expensive to buy or make. If they are suspect, simply replacing them might just be the best idea.<br type="_moz" />

A continuity check will do but the voltage drop across the internal resistance of a wire is very small. What you detect, if you had a problem, might be caused by corrosion at the connections between the extension and anything it is connected to. At any rate, the resistance is very small and hard to detect.

If a problem is suspect, your advise is sound.. replace the extension.

The problem is that our extensions are measured in inches not feet. For instance a 12 inch extension will have such a small internal resistance, that it might be very difficult to read. And, if it had a high resistance, the problem would be evident.. the servo would most likely not work at all and swapping it out would fix the problem.

CGr.

its not that i am having problems with one i bought some servo extensions off of ebay and i was just wondering if there was a way i could check to see how good they where they came from over seas but now a days what electrionic stuff doesnt come frome over there

I'd just hook them up then operate them while wiggling and tugging on them. If they continue working then they'll be fine.

I was going to reply in the same way... However ChuckW's idea of using a meter while performing a WiGGLE test is not a bad idea to help spot breaks or potential problems that may arise due to vibrations.

However voltage drop is not very telling otherwise, on our fairly short cable runs....

I own a Time Domain Reflectometer which I've used on RC cables, and even this fairly sensitive instrument has a hard time with them.

I purchased a boatload of the overseas extentions of various sizes and so far there fine, a good old servo test, plug it in and wiggle the sticks,and move the connector a bit if it works then there OK to use.

on the ones I have the connector is a nice tight fit with no slack, so far, if you notice the servo lead is loose in the connector junk the extension and try a new one.

on the ones I got I paid .01$ the shipping was the cost couple of bucks is all, there fairly well made, there just a wire and a plug not alot too them.

The problem with this is that with vibration, heat, glow fuel, oil, etc. even a tight connector can land will et go.

ALWAYS use a secondary mechanism to keep the connectors affixed.

I've purchased some very inexpensive clips ( $.20 / ea ) from HC/HK, which I use on extensions that I undo all the time.

For more permanent extensions, dental floss, heat shrink tubing, knots, etc. are all better ideas.

Now, I never thought about a TDR. There's an idea..

As I was writing my reply, well, I kept thinking of how difficult it would be to measure such a short cable for anything but a short or open, but I guess what ChuckW suggested is just about the best way to do it.

I buy my extensions from Tower and get "name brand" cables. The cost difference seems to me to be worth the problems that could result from a bad extension.

CGr.

I'm not advocating the voltage drop test to look for losses due to the length of the wire. I realize that they are very short an dlosses form length would be almost none. It is a useful test though to find things like bad terminal crimps, corrosion, broken wires and so on. In the industry I am in we deal with a lot of lower voltage, lower current DC circuits. Often the only way to find resistance issues is to power up the circuit put the meter leads on either side of the suspected problem area and see what the voltage reading is. I generally instruct my technicians that any reading above 50 millivolts is a potential problem. Obvisously larger, higher current circuits will have more acceptable drop.

I was just thinking about doing this on RC extensions though and I realized it would work fine on the positive and negative wires but not so well on the signal wire since it is pulsed. Probably the best thing to do then is keep it simple, put it in the airplane, operate it, pull it, twist it, shake it, etc. and see if it it fails. If it works then call it good.

shure of course, but the point was that if the connector is loose to begin with, its a suspect item,if a connector is loose, or the wires look to be not well done, then there isn't any reason to use a particular part period

I always tape my connections with electical tape, esspecially when there in a low to no access location, like a wing or deep in a fuse where visual inspection is difficult these areas in particular have little chance of fuel exposure but vibration could be a issue.

I would recomend always secure your servo extensions no matter where there used, using the many tried and true methods, like I posted I use plain old tape but there are plenty of ways to do it